var net = require('net');
var server = net.createServer();
//聚合所有客户端
var sockets = [];
//接受新的客户端连接
server.on('connection', function(socket){
  console.log('got a new connection');
  sockets.push(socket);
  //从连接中读取数据
  socket.on('data', function(data){
    console.log('got data:', data.toString());
    //广播数据
    //每当一个已连接的用户输入数据，就将这些数据广播给其他所有已连接的用户
    sockets.forEach(function(otherSocket){
      if (otherSocket !== socket){
        otherSocket.write(data);
      }
    });
    //删除被关闭的连接
    socket.on('close', function(){
      console.log('connection closed');
      var index = sockets.indexOf(socket);
      sockets.splice(index, 1);
    });
  });
});
server.on('error', function(err){
  console.log('Server error:', err.message);
});
server.on('close', function(){
  console.log('Server closed');
});
server.listen(4000);